Modern cataract surgeries are typically followed by implantation of an intraocular lens (IOL) in an eye to enable spectacle free vision post operation. The IOL can be implanted in either an anterior chamber or posterior chamber of the eye. The IOL is required to be of a flexible and foldable material such that an eye surgeon can easily inject the IOL through a small incision into a capsular bag of the eye and further correctly position the IOL. The IOL typically includes an optic with one or more haptics or elements that support the optic.
Position of the IOL, however, cannot be accurately determine pre-operatively. Hence, effective lens position of the IOL is not attained and accounts for around 0.75 diopter (D) error. Moreover, the IOL can move out of position (also referred to decentration) thereby creating loss in effective vision and user dissatisfaction. Some examples of IOLs that have been designed to overcome the above problems are discussed in detail below.
In one example, the IOL, a hydrophilic acrylic IOL, includes a 5 millimeter (mm) optic surrounded by a peripheral groove that is defined by elliptical haptics. The elliptical haptics are perpendicularly oriented to each other and allow for accommodation of both anterior and posterior capsulorrhexis (a continuous circular tear in anterior and posterior capsule, respectively). However, in this example, the eye surgeon should create perfectly sized anterior and posterior capsulorrhexis (slightly lesser than the 5 mm optic) which is a challenging process. Moreover, there is a possibility of stretching the capsular bag, during positioning of the IOL, leading to tearing of the capsular bag. In such cases, the IOL has to be explanted and not implanted.
Postoperative follow-ups of the hydrophilic acrylic IOL have determined non-occurrence of posterior capsule opacification (PCO) and visual axis reproliferation (VAR). Centration stability of the hydrophilic acrylic IOL is also determined to be stable over time. Hence, despite the centration stability and the non-occurrence of the PCO that enable accommodation of complex IOLs, for example Toric IOLs and multifocal IOLs, alignment of the hydrophilic acrylic IOL is still incorrect.
In another example, the IOL, an anti-dysphotopic IOL, includes a grove on an anterior edge near around periphery of the optic. Capsulotomy can be captured in the groove and bulk of the IOL is placed in the capsular bag. However, there are chances that the capsulotomy is not captured. The IOL is also larger in size and requires a wider incision for implantation. Further, haptics in the IOL are thick and are in contact with back of iris of the eye, thereby causing iris chaffing and pigment dispersion over time.
The anti-dysphotopic IOL is used to prevent negative dysphotopsia after cataract surgery. The anti-dysphotopic IOL further provides centration stability due to use of a flange of the anterior edge that overrides anterior capsulotomy. However, the anti-dysphotopic IOL is not successful for prolonged use.
Hence, the IOLs currently in use typically face issues such as difficulty in removal of an ophthalmic viscosurgical device (OVD) from behind the eye, complicated designs and technical difficulty, need of special instruments and injectors, capsulotomy tears, capsular block, the iris chaffing, and the pigment dispersion.